A conventional medical stapler as illustrated in FIGS. 4 through 6 disclosed in Patent Document 1 is well known. FIG. 4 shows orthogonal views of a medical stapler, where 4(a) is a top view, 4(b) is a lateral cross-sectional view, and 4(c) is a front view. FIGS. 5(a) to 5(c) are diagrams describing a sequence for forming a staple. FIG. 6 illustrates staples stored in the magazine, where 6(a) is a side view and 6(b) is a cross-sectional view cut along the line I-I of 6(a). A summary thereof will be described below.
A medical stapler 10′ illustrated in FIG. 4 is constituted by a housing 1, a lever 2, which is rotatably attached to the housing 1, and a magazine 4, which is attached to the housing 1 in a detachable manner and houses multiple staples 3. The magazine 4 includes a rail 5, which is fixed within the magazine 4, an anvil 5a, which is formed by making an edge of the rail 5 thin and bending it, a ram 6, which is arranged in a movable manner to and back from the edge of the anvil 5a, and a biasing member 7, which biases the ram 6 in a direction away from the edge of the anvil 5a. The rail 5 has a convex structure having a high center and a base part on either side, where a predetermined number of staples 3 are aligned so as to straddle the convexity of the rail 5, and both legs of the staples 3 are placed on the base part on either side of the rail 5. These staples 3 are biased toward the anvil 5a on the edge of the rail 5 by an elastic member 8.
The housing 1 and the lever 2 are made of synthetic resin, such as ABS resin, and formed into shapes in consideration of gripping ease and user-friendliness.
The magazine 4 is formed as a separate body from the housing 1, where the lever 2 and the housing 1 are attached thereto to complete the medical stapler 10′. The magazine 4 is molded integrally using transparent ABS resin, allowing external confirmation of remaining number of the staples stored therewithin.
The staples 3 are stored within a receiving space in the magazine 4 where a predetermined number are lined up, and then placed on the rail 5. The staples 3 are formed by bending a rounded, stainless-steel wire rod into a u-shape, and as shown in FIG. 5(a), are formed having pointed legs 3a so as to reduce resistance when both end portions pierce through a living organism. A portion connecting both of the legs 3a and 3a is referred to as a crown 3b, which is a portion that is bent when suturing the living organism. Moreover, each of the staples 3 is stored with the legs 3a tilting in the advancing direction and the crown 3b tilting in the retreating direction, as shown in FIG. 6(a). The stapler may be downsized by tilting them in this manner at a tilt angle α of 45 to 60 degrees.
Note that length of the crown 3b of the stapler 3 is referred to as staple width, herein.
FIG. 5 are diagrams describing a sequence for forming the staple 3 in order to suture a wound. The stapler 10′ is mainly used for suturing a wound on a body surface. When the edge of the stapler 10′ is placed on the diseased portion, and the lever 2 shown in FIG. 4(b) is rotated in direction a by application of force, the ram 6 is driven to the lever 2 and lowered, where the edges of the ram 6 finally touch the crown 3b of the staple 3 as shown in FIG. 5(a). When the ram 6 continues to be lowered even further, the crown 3b is bent in a curved shape, as shown in FIG. 5(b). The legs 3a pierce through the skin at this time. When the ram 6 is lowered even further, as shown in FIG. 5(c), the crown 6 is bent at a right angle at both ends of the anvil 5a, the legs 3a become parallel to the anvil 5a in the living tissue beneath the wound, and the staple 3 is bent into a quadrangle, thereby completing a single suture. At this time, only the central portion of the crown 3b appears above the skin, and the other three sides of the quadrangle are buried in the living tissue. Width of the anvil 5a corresponds to the lateral dimension of the quadrangle formed when the staple 3 is formed.
When eliminating the force applied on the lever 2, the lever 2 is rotated in direction b of FIG. 4(b) due to energization force of the bias member 7, the ram 6 is raised, and then returned to the initial position. Repeating the above operation feeds the staples 3 one after another and suturing is repeated.
FIG. 6 illustrates the staples 3 stored in the magazine 4, where 6(a) is a side view and 6(b) is a cross-sectional view cut along the line I-I of 6(a).
A predetermined number of the staples 3 are lined up on the rail 5, pushed by the elastic member 8, and pushed out toward the anvil 5a. Moreover, as described above, the staples 3 in the drawing is slanted at a tilt angle α of 45 to 60 degrees so that the legs 3a tilt in the advancing direction but the crown 3b tilts in the retreating direction. As shown in FIG. 6(b), a staple receiving space 9 of the magazine 4 has width defined by walls 4a and 4b on the left and right sides in the advancing direction, and top and bottom defined by a roof 4c and top surface of the bases of the rail 5. If there is no gap in the vertical direction between the roof and the staples 3 and the width (lateral) direction, the staples 3 cannot progress within the receiving space 9, and the stapler is thus unusable.
Therefore, an appropriate gap is reserved in the width direction and the vertical direction, assuring movement of the staples 3. However, the staples 3 are made by bending round bars, each of the staples 3 are detached, and thereby multiple staples are not lightly connected as are staples for stationary usage. Accordingly, each of the staples 3 is arranged on the bases of the rail 5 and therefore cannot be moved therebelow; however, it is movable above and to the left and right. As a result, there is the following problem in the case where a gap between the left and right walls 4a and 4b is to large. That is, when adjacent staples 3 shift to the left and right, and if the elastic member 8 is then pressed, the staples 3 are pushed and moved toward the left and right walls 4a and 4b orthogonal to the advancing direction, and thrust against the walls 4a and 4b, stuck in without being able to move (which is referred to as “jamming”), and thereby the medical stapler 10 becoming unusable.
Moreover, the staples 3 have a tilt at an angle α within the receiving space 9, as described before; however, when progression is not smooth, the staples 3 rise up and the tilt angle α increases. As a result, the front edges of the sharp legs 3a catch onto the surface of the rail 5, leading to jamming of the staples.
Patent Document 2 proposes relative twisting of a pair of legs of a stapler to provide stable supply of staples. Twisting allows control of the twisted state, allowing smooth supply of staples. However, this configuration does not resolve the problem of jamming of staples due to a gap within the receiving space, and problem of jamming of staples due to catching.
Furthermore, the conventional magazine 4 has an integral structure resulting from injection molding of synthetic resin, formation of space for storing the ram 6 and the biasing member 7 is necessary, and it has a complex form. Therefore, there are problems of a complex metal structure and high manufacturing cost of the magazine.